He had started modestly about twenty years ago by cutting up an old plastic tub, which he had placed under the gutter of the house. A small reserve of barely 200 L of water, which he used to water flowers and potted plants. “It was too tight for the vegetable garden. Since then, Michel has gradually increased his storage capacity, recovering two tanks of 1,000 L each, before transforming his old septic tank into a reserve of 3,000 L hidden underground. With some old drilled pipes, he also made a drip, which he buries underground when he sows beans.
Everything is fed with rainwater collected from the roof of his house. Thanks to his winter reserves, this resident of Saint-André-des-Eaux (Loire-Atlantique) no longer takes out a drop of drinking water to water his garden or his 150 m² vegetable patch. “Before, I was already watering as little as possible but it was raining more. Today is warmer, drier. But all I need is a good stormy rain to fill everything up,” says the young retiree.
Like him, many French people have equipped themselves to collect rainwater, often to water their gardens. Over the past two years, the use of these plastic tanks has greatly increased, under the effect of the heat wave and the worrying droughts that have hit our country. “The demand has been phenomenal for a year, and that’s good. Collecting rainwater is just a common sense practice, people reclaim it because they see that it rains differently. They want to be more independent, to gain in autonomy”, observes Thomas Contentin, director of the company Aquality and president of the French industrialists of rainwater (Ifep).
The abnormally low level of waterways and groundwater in 2022 had forced almost all departments to ban the watering of gardens last summer. Faced with this observation, more and more local authorities are encouraging their inhabitants to equip themselves with rainwater collectors. Nantes, for example, has just announced aid of €50, valid from September. The Eau du Bassin Rennes local authority will offer a check for €25 and a 10% discount in most gardening stores from Thursday 6 April. “According to our estimates, 10 to 15% of the drinking water we distribute is used in the garden. We can see that the margin for progress is significant,” explains Ludovic Brossard, vice-president of the community.
Should we fear a shortage of equipment?
If the cost of plastic tanks has increased in recent years, their purchase quickly remains profitable for individuals, to the point of making them an increasingly sought-after product. Should we be worried about a shortage with the proliferation of local government incentive policies? ” There is no risk. The plastics industry is ready”, assures Thomas Contentin.
But is there a risk for the resource in generalizing these installations, which intercept part of the precipitation? “No, because the capture surface is ultimately very low. It is even virtuous. Water is intercepted as it naturally falls before it gets dirty on sidewalks and roads and needs to be treated. In most French cities, rainwater is mixed with wastewater. During storms, they come to saturate the treatment plants, “says the president of Ifep. “On the contrary, we capture the water to store it and pour it back into the environment when it needs it,” continues Ludovic Brossard.
“No comparison possible” with bedpans
Should we draw a parallel with the basins that are so debated? “There is no possible comparison. The volumes we are talking about are very low. And they are not pumped into the rivers, ”continues the Rennes elected official.
Although the use of rainwater is widespread for watering gardens, it is much less so inside houses. Sector professionals hope that Emmanuel Macron’s recent comments on the reuse of wastewater will help to move the issue forward. “We can absolutely use the rainwater for the toilets or the washing machine. For an average household, we are talking about a hundred liters of water per day, and every day. It is considerable. We have long been accustomed to turning on a tap without trying to find out where the water came from and where it left. In view of the challenges ahead, we must change our practices, go further,” warns Thomas Contentin. The latter ensures that a rainwater recovery system for toilets is “very easy” in a new construction. “You just have to provide a second network so that they don’t get mixed up.” While acknowledging that for the old, “it’s more complicated”.